Consider though that a higher intensity recovery interval will cause VO2 to remain elevated between work intervals, meaning onset kinetics (how quickly VO2 changes, in this case rises to our ‘near-VO2max’ target) will be faster during subsequent intervals.
Also the power output required to elicit ‘near-VO2max’ from a higher baseline during the rest interval, will be lower for the same reason. More VO2 during that harder recovery interval had to go toward continued locomotion instead of actual recovery processes, so it takes a lower workload to perturb metabolic homeostasis and elicit a similar VO2 response.
So IMO it depends if the goal of your ‘VO2max’ session is to maximize total work (power output) or maximize duration near VO2max. Both are legitimate, and you could optimize either way with different interval programming. And you can definitely go overboard on recovery intensity, carry too much fatigue into the next work interval, and not be able to subsequently reach a high VO2 at all.
Edit: I actually prefer easy but short recovery intervals, to give the legs a chance to stop burning, but to keep systemic VO2 high. Other than that I don’t have a firm physiological rationale. Just personal preference.